Pipelayer and method of loading pipelayer or excavator for transportation

ABSTRACT

Embodiments of the present invention generally relate to a pipelayer and a method for of loading a pipelayer or excavator for transportation. One embodiment includes a method for transporting a pipelayer or excavator from a first work site to a second worksite via a public road. The method includes acts of: raising the pipelayer or excavator off of track shoes of the pipelayer or excavator; removing a first track assembly from the pipelayer or excavator using a boom of the pipelayer or a boom assembly of the excavator; loading the first track assembly onto a first trailer of a first tractor-trailer using the boom of the remaining pipelayer or the boom assembly of the remaining excavator; removing the second track assembly from the pipelayer using the boom of the remaining pipelayer or the boom assembly of the remaining excavator; and loading the second track assembly onto the first trailer using the boom of the remaining pipelayer or the boom assembly of the remaining excavator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/125,691, filed May 10, 2005, which is a continuation-in-part(petition pending) of International Application No. PCT/US2003/007613,filed Mar. 11, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a pipelayer anda method for of loading a pipelayer or excavator for transportation.

2. Description of the Related Art

FIG. 1 is a front view of a prior art pipelayer 10. The pipelayer 10 istypically used for the construction of underground pipelines whichtransport hydrocarbons, such as natural gas or gasoline. Typicaloperation of the pipelayer includes raising, carrying, and loweringheavy pipe 12. The pipelayer 10 is a crawler or tractor-type vehiclehaving a maneuverable boom 42 disposed on a side thereof. For thisreason, the pipelayer 10 is referred to as a sideboom.

The pipelayer 10 further includes a main frame assembly 14 having firstand second opposed sides 16 and 18 and a radiator guard 20. Thepipelayer 10 includes first and second endless self-laying trackassemblies 22, 24, with each of the track assemblies 22, 24 having aroller frame. A rigid cross bar 28 and a pivot shaft connect each trackassembly 22, 24 to a respective side 16, 18 of the main frame assembly14. A pipelayer frame 32 has a first portion 34 secured to the mainframe assembly 14 and a second portion 36 secured to one of the rollerframes by a plurality of fasteners. The first portion 34 is joined tothe second portion 36 by a pin arrangement 40. The boom arm 42 has afirst end portion 44, pivotally connected to the pipelayer frame secondportion 36, and a second end portion 46 supporting a cable operated loadblock assembly 48. A drawworks 50 runs a cable 52 in and out to raiseand lower the block assembly 48 and the pipe 12. A fluid operatedcylinder 54 has a first end portion 56 connected to the pipelayer frame32 and a second end portion 58 releasably connected to the boom armsecond end portion 46. A counterweight 55 is attached to the main frame14. The counterweight 55 may also be secured to one of the roller framesby a counterweight frame (not shown) similar to the pipelayer frame 32.

The boom arm 42 of the pipelayer 10 cannot rotate without driving thetrack assemblies 22, 24. To deliver a piece of pipe from the pipedelivery vehicle located on an opposite side of the pipelayer relativeto the pipeline trench, the pipelayer would have to drive the trackassemblies 22, 24 in order to turn 180 degrees so that the boom wouldface the pipe delivery vehicle, pick up the pipe, and drive the trackassemblies 22, 24 in order to turn 180 degrees so that the boom arm 42would face the trench in order to deliver the piece of pipe.

Further, the pipelayer 10 is a specialized vehicle. It is not configuredto perform other jobs at a pipeline work site, such as excavation. Whenpipelaying duties are complete, the pipelayer may idle in a yard untilrequired again, which may be a substantial period of time.

The boom arm 42, the pipelayer frame 32, and the counterweight frameincrease the width of the pipelayer 10 versus traditional crawlers. Thisincreased width causes difficulty in transporting the pipelayer from onework site to another over public roads as the increased width means thatthe pipelayer will not fit on a standard trailer without requiringpermits and/or pilot vehicles which increase the expense associated withtransportation. Alternatively, the boom arm 42, the pipelayer frame 32,the counterweight 55, and the counterweight frame of the pipelayer 10may be removed for transportation. However, this substantial disassemblyof the pipelayer 10 increases the labor and thus also increasestransportation costs.

Therefore, there exists a need in the art for a pipelayer thatfacilitates the pipelaying operation, may be used for other purposes,and/or possesses the ability to be transported via public roads withminimal disassembly.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to a pipelayer anda method for of loading a pipelayer or excavator for transportation. Oneembodiment includes a method for transporting a pipelayer or excavatorfrom a first work site to a second worksite via a public road. Themethod includes acts of: raising the pipelayer or excavator off of trackshoes of the pipelayer or excavator; removing a first track assemblyfrom the pipelayer or excavator using a boom of the pipelayer or a boomassembly of the excavator; loading the first track assembly onto a firsttrailer of a first tractor-trailer using the boom of the remainingpipelayer or the boom assembly of the remaining excavator; removing thesecond track assembly from the pipelayer using the boom of the remainingpipelayer or the boom assembly of the remaining excavator; and loadingthe second track assembly onto the first trailer using the boom of theremaining pipelayer or the boom assembly of the remaining excavator.

Another embodiment includes a pipelayer. The pipelayer includes anundercarriage and a main assembly supported by the undercarriage so thatthe main assembly may rotate relative to the undercarriage. Theundercarriage includes a lower frame and two track assemblies. Eachtrack assembly includes a track frame removably attached to the lowerframe and a track shoe supported by the track frame so that the trackshoe may move around the track frame. The main assembly includes a mainframe and a boom pivoted to the main frame.

Another embodiment includes a method of using a pipelayer. The methodincludes acts of: providing a pipelayer; removing a counterweight of thepipelayer; and operating the pipelayer on a steep grade without thecounterweight.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIGS. 2-6 are various views of a pipelayer, according to one embodimentof the present invention.

FIG. 2 illustrates a perspective view of the pipelayer, wherein alongitudinal axis L_(mf) of the main assembly is perpendicular to alongitudinal axis L_(uc) of the undercarriage. FIG. 2A is a schematicillustrating a configuration of the pipelayer so that the boom pivot iswithin both a rectangular footprint and a rectangular tipping fulcrum ofthe pipelayer.

FIG. 3 illustrates another perspective view of the pipelayer, whereinthe longitudinal axis L_(mf) of the main assembly is parallel to alongitudinal axis L_(uc) of the undercarriage.

FIG. 4 illustrates another perspective view of the pipelayer, whereinthe longitudinal axis L_(mf) of the main assembly is parallel to alongitudinal axis L_(uc) of the undercarriage.

FIG. 5 illustrates an orthogonal view of the pipelayer, wherein thelongitudinal axis L_(mf) of the main assembly is perpendicular to alongitudinal axis L_(uc) of the undercarriage.

FIG. 6 illustrates another orthogonal view of the pipelayer, wherein thelongitudinal axis L_(mf) of the main assembly is parallel to alongitudinal axis L_(uc) of the undercarriage.

FIGS. 7-12 illustrate acts of a method for partially disassembling thepipelayer and loading the pipelayer on two tractor-trailers (onlytrailer shown) for transporting the pipelayer between jobs, according toanother embodiment of the present invention.

FIG. 7 illustrates the outriggers in the extended position and one ofthe track assemblies loaded on a first trailer.

FIG. 8 illustrates the other one of the track assemblies loaded on thefirst trailer.

FIG. 9 illustrates an act of backing the second trailer underneath theremaining pipelayer.

FIG. 10 illustrates axles of the second trailer passing underneath theremaining pipelayer.

FIG. 11 illustrates the remaining pipelayer loaded on the secondtrailer.

FIG. 12 illustrates the boom and counterweight loaded on a thirdtrailer.

FIG. 13 illustrates a short pipe transporting act of the pipelayingoperation.

FIG. 14 illustrates a short pipe centering/joining act of the pipelayingoperation.

FIG. 15 illustrates long pipe centering/joining act of the pipelayingoperation.

FIG. 16 illustrates long pipe centering/joining act of the pipelayingoperation performed on a grade.

FIG. 17 is an orthogonal view of a pipelayer, according to analternative embodiment of the present invention.

FIGS. 18A-D illustrate a removable counterweight system (RCW), accordingto another embodiment of the present invention. FIG. 18A is a side viewof the RCW in a first position where a counterweight is engaged with themain frame. FIG. 18B is a side view of the RCW in a second positionwhere the counterweight is dis-engaged with the main frame and set onthe ground. FIG. 18C is a front view of the counterweight. FIG. 18D is asection view of FIG. 18C taken along line 18D-18D.

FIGS. 19-21 illustrate an excavator and acts of a method for partiallydisassembling the excavator and loading the excavator on two or moretractor-trailers for transporting the excavator between work sites overpublic roads, according to another embodiment of the present invention.

FIG. 19 illustrates the outriggers in the extended position and a firstact of loading one of the track assemblies on the first trailer.

FIG. 20 illustrates a second act of loading one of the track assemblieson the first trailer.

FIG. 21 illustrates the remaining excavator loaded on the secondtrailer.

FIGS. 22 and 23 illustrate acts of a method for partially disassemblingthe excavator (or pipelayer) and loading the excavator on two or moretractor-trailers (only trailer shown) for transporting the excavatorbetween work sites over public roads, according to another embodiment ofthe present invention.

FIG. 22 illustrates the excavator driven over the trailer after agooseneck of the trailer has been removed.

FIG. 23 illustrates the excavator lifted off the track shoes by thegooseneck jack.

DETAILED DESCRIPTION

FIGS. 2-6 are various views of a pipelayer 100, according to oneembodiment of the present invention. The pipelayer 100 includes a mainassembly 150 a mounted on an undercarriage 150 b so that the mainassembly 150 a may rotate relative to the undercarriage 150 b. FIG. 2illustrates a perspective view of the pipelayer 100, wherein alongitudinal axis L_(mf) of the main assembly 150 a is perpendicular toa longitudinal axis L_(uc) of the undercarriage 150 b. FIG. 3illustrates another perspective view of the pipelayer 100, wherein thelongitudinal axis L_(mf) of the main assembly 150 a is parallel to alongitudinal axis L_(uc) of the undercarriage 150 b. FIG. 4 illustratesanother perspective view of the pipelayer 100, wherein the longitudinalaxis L_(mf) of the main assembly 150 a is parallel to a longitudinalaxis L_(uc), of the undercarriage 150 b. FIG. 5 illustrates anorthogonal view of the pipelayer 100, wherein the longitudinal axisL_(mf) of the main assembly 150 a is perpendicular to a longitudinalaxis L_(uc) of the undercarriage 150 b. FIG. 6 illustrates anotherorthogonal view of the pipelayer 100, wherein the longitudinal axisL_(mf) of the main assembly 150 a is parallel to a longitudinal axisL_(uc) of the undercarriage 150 b.

The main assembly 150 a includes a main frame 105, an optional adaptor110, a cab 115, a boom 120, a piston and cylinder assembly 125, a winch130, a pulley block 135, a load block 140, a counterweight 145, and anengine 147. The main frame 105 has a first side 105 a and a second side105 b distal from the first side 105 a. Attached to the first side 105 aare the optional adaptor 110 and the operator's cab 115. Pivoted to theadaptor 110 at 120 p is a first longitudinal end of the boom 120. Asused herein, the term pivoted or pivot includes a single axis pivot,such as a hinge, and a double axis pivot, such as a universal joint. Thepiston and cylinder assembly (PCA) 125 is also pivoted to the adaptor110 and to the boom 120 so that extension of the PCA 125 will lower theboom and retraction of the PCA will raise the boom 120. The adaptor 110may be removably attached to the frame 110 to allow the boom 120 to bereplaced with an excavator boom (not shown) or a crane boom (not shown).Alternatively, the boom 120 may be directly pivoted to the main frame105.

Attached near the first longitudinal end of the boom 120 is a winch 130.The winch 130 includes a drum having a cable 132 (only partially shown)wrapped therearound. The drum is rotatable relative to a housing of thewinch. The drum may be driven by a hydraulic motor (not shown). Pivotedto a second longitudinal end of the boom 120 is a pulley block 135. Hungfrom the pulley block 135 by the cable 132 is a load block 140. Each ofthe blocks 135, 140 include a plurality of pulleys or sheaves. The cable132 extends from the winch drum along the boom 120 and around thesheaves of the pulley block 135 and load block 140 in order to achieve amechanical advantage. Unwinding of the cable 132 from the drum lowersthe load block 140 and winding of the cable 132 around the drum raisesthe load block 140.

The boom 120 may be an A-frame and may include two primary structuralmembers 120 a, b and two cross bars. The boom 120 may also be asymmetricin that one of the primary structural members 120 a may extend from themain frame 105 at a first angle relative to a vertical axis that is lessthan a second angle relative to the vertical axis at which the other one120 b of the primary structural members extends from the main frame. Theasymmetric design allows better visibility for the operator and improvesloading characteristics of the boom as compared to a symmetric design.The structural members 120 a, b may be made from high strength steelsquare tubing. Alternatively, the boom may be a symmetric A-frame orinclude only a single structural member.

Attached to the second side 105 b is a counterweight 145. Housed in thesecond side 105 b of the main frame is an engine 147. The engine 147 maydrive a hydraulic pump (not shown) and a generator or alternator (notshown) for providing hydraulic or electrical energy to components, suchas the cab sensors, the PCA 125, and the winch 130. Associated hydraulicand electrical circuitry (not shown) interconnecting these componentsmay also be provided. The engine may be a diesel engine or analternative fuel engine. Examples of alternative fuel engines includediesel-electric hybrid and hydrogen fuel-cells. The diesel-electrichybrid may use a smaller diesel engine and a bank of batteries (notshown) which would allow operation of the pipelayer 100 withoutoperation of the diesel engine.

Rotation of the main assembly 150 a relative to the undercarriage 150 band support for the main assembly 150 a by the undercarriage 150 b areprovided by a rotary drive mechanism (not shown) and a bearing 155. Therotary drive mechanism may include a hydraulic or electric motor (notshown) attached to the main frame and rotationally coupled to a pinion(not shown) which meshes with a gear (not shown) rotationally coupled tothe undercarriage 150. Operation of the motor will cause the mainassembly 150 a to rotate relative to the undercarriage 150 b. The rotarydrive mechanism may further include a turn lock mechanism (not shown)for selectively rotationally coupling the main assembly 150 a relativeto the undercarriage 150 b. The turn lock mechanism may include a geartooth (not shown) selectively engageable with the gear via operation ofa hydraulic cylinder or electic motor (not shown) and a proximity switchto verify engagement of the tooth with the gear. Engagement of the gearwith the tooth rotationally couples the main assembly 150 a to theundercarriage 150 b. Verification of engagement by the proximity switchalso prevents operation of the motor.

Alternatively, the turn lock mechanism may include a disk (not shown)incorporated in the motor and a retaining mechanism for retaining thedisk. The turn lock mechanism is such that when the rotary motor isstopped, the disk is retained by the retaining mechanism to fix a rotorof the motor so as not to rotate, and when the motor is started, thedisk is hydraulically or electrically disengaged from the motor, therebyfreeing the rotor.

The cab 115 is includes walls, a ceiling, and windows to protect theoperator from weather conditions and allow visibility for the operator.Placement of the cab 115 on the main frame 105 a may allow the operatorunobstructed view to the front, left, and/or right. The cab 115 furtherincludes a seat (not shown), operating instruments (not shown), andoperating controls (not shown). The cab may further include a loadmanagement system (LMS). The LMS is a microprocessor based system andincludes a variety of sensors in communication with the microprocessorto calculate and display boom angle, boom capacity, and/or the load onload block. The LMS may include a database of boom capacities forvarious operating positions and surface grades. The LMS may alert theoperator, with audio and/or visual warnings, when rated capacity isimminent, reached, and/or exceeded.

The LMS may allow an operator to simulate a multi-position pipelayingoperation before performing the operation. The operator may move thepipelayer through various expected positions of the operation and notethe load capacity at each position. Alternatively, the LMS may beprogrammed to record the capacity at each position and simulate theoperation once the actual load is known. The operator then may pick upthe load and estimate whether the load will exceed the load capacity atany of the expected positions. If so, he may then re-configure theexpected positions until the load may be safely handled. The LMS mayalso warn the operator of an impending two-block event (when the loadblock contacts the pulley block).

The LMS system may also log a history of the lifts performed by thepipelayer 100, and this data can be downloaded to a computer for lateranalysis. The LMS may include an external, boom-mounted light bar toprovide a simple visual indicator of approximate load on hook. The lightbar may include a color scheme of lights. For example, green lights meanthe crane is under a light load, yellow indicates a heavier load, and ared signals a high load condition. The LMS may also monitor grade of thesurface that the pipelayer is operating on and calculate and display theproper load value that corresponds to the grade. The LMS may communicatewith an LMS of a second pipelayer 100 and indicate the load distributionbetween the two pipelayers for pipelaying operations performed intandem. With this information, the operators may coordinate activitiesto ensure that an optimal load distribution is maintained.

The undercarriage 150 b includes a lower frame 160 attached to thebearing 155 and two track assemblies 175, each removably attached to thelower frame 160. Each of the track assemblies 175 includes a track frameand one or more rollers 180 a,b, such as sprockets, operatively coupledto a track shoe or belt 185. The track shoe 185 extends around the trackframe and is movable relative to the track frame. The rollers 180 a, bare supported by the track frame so that the rollers may rotate relativeto the track frame. One of the rollers 180 a, b may be a drive sprocketand the other an idler roller. A rotor of an electric or hydraulic trackmotor (not shown) may be rotationally coupled to the drive sprocket anda housing of the track motor may be attached to the track frame. Aconduit, such as an electrical cable or hydraulic hose, may extend fromthe main frame 105 to the track motor. The conduit may be connected tothe track motor by a quick-connect fitting. Operation of the track motorwill cause movement of the track shoe 185 relative to the track frame.

FIG. 2A is a schematic illustrating configuration of the pipelayer 100so that the boom pivot 120 p is within a rectangular outer footprintOFP, a rectangular tipping fulcrum TF, and a rectangular inner footprintIFP of the pipelayer 100. The outer footprint OFP is defined by outersides of the track shoes 185. The tipping fulcrum TF is defined bylongitudinal centerlines of each of the track shoes 185 and bylongitudinal centerlines of the rollers 180 a, b. The inner footprintIFP is defined by inner sides of the track shoes 185. Since the boompivot 120 p is within the footprints OFP, IFP and the tipping fulcrum TFin the perpendicular and parallel positions of FIGS. 5 and 6, then it isalso within the footprints and tipping fulcrum for any rotationalposition of the main frame relative to the undercarriage (represented bythe dashed circle). Alternatively, the boom pivot 120 p may be disposedbetween the outer footprint OFP and the tipping fulcrum TF or the innerfootprint IFP and the tipping fulcrum TF.

FIGS. 7-12 illustrate acts of a method for partially disassembling thepipelayer 100 and loading the pipelayer on two or more tractor-trailers200 a-c (only trailer shown and gooseneck removed for simplicity) fortransporting the pipelayer 100 between work sites over public roads,according to another embodiment of the present invention. The trailers200 a-c may be standard lowboy flatbed trailers. FIG. 7 illustratesoutriggers 165 in the extended position and one of the track assemblies175 loaded on a first trailer 200 a. FIG. 8 illustrates the other one ofthe track assemblies 175 loaded on the first trailer 200 a.

To facilitate dis-assembly of the pipelayer 100 for transport andre-assembly of the pipelayer 100 for delivery to the next job site, eachof the track assemblies 175 may include one or more lugs 190 attached tothe track frame. Each of the lugs 190 may include a hook 190 a and ahole 190 b. Each of the lugs 190 is received in an opening 195 a of abracket assembly 195 of the lower frame 160. The bracket assembly 195may include two plates 195 d spaced apart to define the opening 195 a,each plate 195 d attached to the lower frame 160. Fasteners 195 b, c(i.e., a bolt or a pin) may each be disposed through corresponding holesin the plates 195 d. To attach each track assembly 175 to the lowerframe 160, the fastener 195 c is removed and the hook 190 a is engagedwith the fastener 195 b and the fastener 195 c is then inserted throughholes in the plates 195 d and the hole 190 b and then locked to thetrack frame (i.e. by a nut or a clip). The track conduit may then beconnected to the track motor by the quick-connect fitting.Alternatively, the lug 190 may be attached to the lower frame 160 andthe bracket assembly 195 may be attached to the track frame.

Alternatively, each of the track motor housings may be attached to thelower frame 160 and each rotor thereof rotationally coupled to arespective drive roller via a removable shaft. The shaft would beremovably rotationally coupled at the track motor. Alternatively, eachof the track assemblies 175 may be attached to the lower frame 160 byone or more telescoping axles (not shown). The telescoping axles wouldextend to provide a wide footprint for pipelaying operation and retractto provide a narrow footprint for transportation.

To further facilitate dis-assembly for transport and re-assembly fordelivery of the pipelayer 100, one or more outriggers 165 areselectively pivotal relative to the lower frame. Each outrigger mayinclude a first arm 165 a, a second arm 165 b, a third arm 165 c, and apad 165 d. The first arm 165 a is selectively pivotal relative to thelower frame 160. The second arm 165 b is selectively pivotal relative tothe first arm and is retractable within the first arm 165 a. The thirdarm 165 c is selectively longitudinally coupled to the second arm 165 band is retractable within the third arm 165 c. The pad 165 d is pivotedto the third arm 165 c. The outriggers 165 are operable between anextended position and a retracted position.

Starting from a retracted position (FIG. 2), the first arm 165 a ispivoted from a retracted position against a side of the lower frame 160to an extended position about perpendicular to the side of the lowerframe 160. The first arm 165 a may then be locked into position. Thesecond arm 165 b is then extended from within the first arm 165 a. Thesecond arm 165 b may begin to pivot downward as it is being extended ormay be locked into a position parallel to the first arm. When the secondarm 165 b is fully extended it either pivots to a perpendicular positionrelative to the first arm 165 a or unlocked so that it may pivot to sucha position. The second arm 165 b is then locked into the perpendicularposition. The third arm 165 c and the pad 165 d may then be extendedfrom within the second arm 165 b. As the third arm 165 c extends, thepad 165 d will contact the ground and begin to lift the pipelayer off ofthe track shoes 185. The arms 165 may be coordinated so that all of thearms operate simultaneously. Once the third arm 165 c is fully extended,the third arm 165 c may be locked into position. The outrigger 165 isthen fully actuated.

The track assemblies 175 may then be removed. To operate the outrigger165 to the retraced position the above recited process is reversed.Operation of the outrigger 165 may be fully automated and controlledfrom the cab and/or wirelessly by a remote control (not shown) so thatthe operator may view operation of the outrigger 165 from the ground.Automation of the outrigger 165 operation may be accomplished by theprovision of a hydraulic or electric motor or piston (not shown) topivot the first arm 165 a and hydraulic or electric lines (not shown) toactuate the second 165 b and third 165 c arms and the lockingmechanisms.

The outriggers 165 are operated to lift the pipelayer 100 off of thetrack shoes 185. The fasteners 195 c are removed. The boom 120 and theload block 140 are used to lift the track assembly 175 from the lowerframe 160. To accomplish this, the boom 120 may be raised to asubstantially vertical position and the load block 140 may be lowered tothe track assembly 175 that is being removed. The track assembly 175 maybe prepared for loading by attaching a clamp 250 that grasps edges ofthe track assembly 175 and has a lifting lug for connection to the loadblock 140. Alternatively, chains with hooks (not shown) could be usedinstead of the clamp 250. The load block 140 may be raised to lift thetrack assembly 175 from the lower frame 160. The boom 120 may then belowered to move the track assembly 175 over the trailer. The load block140 may then be lowered to set the track assembly 175 onto the trailer200 a. Removal of the second track assembly 175 is similar to that ofthe first track assembly 175 with the addition that the main assembly150 a may be rotated so that the cab 115 faces the second track assembly175 and then rotated back after the second track assembly 175 is securedso that the second track assembly 175 may be placed on the trailer 200a. Alternatively, the trailer 200 a may instead be moved adjacent to thesecond track assembly 175.

FIG. 9 illustrates an act of backing the second trailer 200 b underneaththe remaining pipelayer 100 (minus the two track assemblies 175). FIG.10 illustrates axles of the second trailer passing underneath theremaining pipelayer 100. FIG. 11 illustrates the remaining pipelayer 100loaded on the second trailer. After the track assemblies 175 have beenremoved and loaded on the first trailer 200 a, the second trailer 600 bis aligned for backing up underneath the remaining pipelayer 100. Thesecond trailer 600 b is positioned so that a longitudinal axis of thetrailer is perpendicular to the longitudinal axis L_(uc) of theundercarriage 150 b. This is because the length of the lower frame 160may be equal to or less than or substantially equal to or less than awidth of the second trailer 200 b whereas the width of the lower frame160 may be greater or substantially greater than the width of the secondtrailer 200 b. The main assembly 150 a may be oriented so that the cab115 faces the second trailer 200 b so that the operator may view thesecond trailer 200 b backing up. Alternatively, the main assembly 150 amay be oriented so that the cab 115 faces away from the second trailer200 b and the operator may exit the cab 115 and view the backing up ofthe trailer 200 a from the ground.

FIG. 10 illustrates axles of the second trailer 200 bpassing underneaththe remaining pipelayer 100. Backing up of the second trailer 200 b thencommences. The jack assemblies 165 provide sufficient clearance foraxles of the second trailer 200 b to pass underneath the remainingpipelayer 100. Before finishing the backing up of the second trailer 200b, the main assembly 150 a may be rotated 180 degrees (or may already bein that position) so that the truck operator may place the counterweight145 or second side 105 b of the main frame 105 in substantial verticalalignment with a front end of the second trailer 200 b (the endproximate the tractor).

FIG. 11 illustrates the remaining pipelayer 100 loaded on the secondtrailer 200 b. Once the remaining pipelayer 100 is aligned with thefront end of the second trailer 200 b, the jack assemblies 165 areretraced until the lower frame 160 rests on the second trailer 200 b.The jack assemblies 165 may then be fully actuated to the retractedposition for transport. The boom 120 may then be lowered to a horizontalor nearly horizontal position. The boom 120 may hang over a rear end ofthe second trailer 200 b. A stinger or flip trailer 205 may be hitchedto the rear end of the second trailer 200 b to contain the overhang(depending on the length of the overhang and the local transportationlaws). Alternatively, a shorter boom may be used so that there is nooverhang. The pipelayer 100 may then be transported to another worksiteusing the two tractor-trailers 200 a, b.

FIG. 12 illustrates the boom and counterweight loaded on a third trailer200 c. If, for example, the route to the next work site crosses a loadzoned bridge, it may be necessary to reduce the weight of the secondtrailer 200 b. The counterweight 145 and the boom 120 may then beremoved and transported on a third trailer 200 c. Alternatively, thecounterweight 145 and the boom 120 may be removed prior to loading theremaining pipelayer 100 onto the second trailer 200 b. The stingertrailer 205 would not be used for the second trailer 200 b. As shown,the boom 120 is loaded with the winch 130 facing the third trailer 200 cand supporting the first end of the boom 120. Alternatively, the boom120 may be loaded with the winch 130 facing away from the third trailer200 c and a block (not shown) may be used to support the first end ofthe boom 120.

The PCA 125 may be left on the remaining pipelayer 100, may be removedwith the boom 120, or may be removed from both the boom 120 and theremaining pipelayer 100. If the PCA 125 is left on the remainingpipelayer 100, a free end may be supported by a bracket (not shown). Ifthe PCA 125 is removed from both the boom 120 and the remainingpipelayer 100, then it may be transported on either the second 200 b orthe third trailer 200 c. Alternatively, if the adaptor 110 is used, theadaptor 110 and the boom 120 together (disposing of the need todisassemble the PCA 125) may be loaded on the third trailer 200 c (withthe counterweight 145) or the boom 120 may be separated from the adapter110 and loaded as shown. Alternatively, only one of the boom 120 and thecounterweight 145 may be removed from the remaining pipelayer 100 andloaded on the third trailer 200 c.

FIGS. 13-16 illustrate a pipelaying operation using one or morepipelayers 100, according to anther embodiment of the present invention.FIG. 12 illustrates a short pipe transporting act of the pipelayingoperation. FIG. 13 illustrates short pipe centering/joining act of thepipelaying operation. FIG. 14 illustrates long pipe centering/joiningact of the pipelaying operation. FIG. 15 illustrates a centering/joiningact of the pipelaying operation performed on a grade.

In the pipelaying operation, the following acts are repeated: (a) shortpipe transporting: short pipes 336 stacked on a material handlingvehicle 335 are moved to a place near a trench 337 and arranged in aline; (b) short pipe centering/joining: an adequate number of shortpipes 336, which have been aligned in the place near the trench 337 bythe short pipe transporting act, are joined by welding into a long pipe338; and (c) long pipe centering/joining act: the long pipe 338 preparedby the short pipe centering/joining act is joined by welding to thepipeline 339 under construction.

As shown in FIG. 13, a working field WF is formed in the short pipetransporting operation on the right of the trench 337, which has beendug. In the working field WF, a traveling space RS₁ for the pipelayer100 and a traveling space RS₂ for the material handling vehicle 335 arearranged in this order from the side of the dug trench 337, so that thepipelayer 100 and the material handling vehicle 335 can travel togetherin an operating direction parallel with the dug trench 337. After theself-propulsion of the undercarriage 150 b allows the pipelayer 100 tomove the distance corresponding to the planned pitch of alignment of theshort pipes 336 in the operating direction, the main assembly 150 aturns about to take one of the short pipes 335 out of the materialhandling vehicle 335 and place it near the dug trench 337. Each of theshort pipes 336 are prepared for laying by wrapping a sling Ttherearound. By repeating this operation, some or all the short pipes336 stacked on the material handling vehicle 335 are moved to andaligned in the place near the dug trench 37.

In the short pipe centering/joining act, as shown in FIG. 14, the shortpipes 336 aligned in the place near the dug trench 337 are raised to alevel suited for welding operation and the are centered to makelongitudinal axes of adjacent short pipes 336 a, 336 b coincident witheach other. Centering of the short pipes 336 is performed by cooperationof a plurality of pipelayers 100 based on an instruction from thehoistman HM.

In the long pipe centering/joining act, as shown in FIG. 15, an end 338a of the long pipe 338 and an end 339 a of the pipeline 339 underconstruction are raised to a level suited for welding operation andcentered to make longitudinal axes of the ends 338 a, 339 a coincidentwith each other. Centering of the ends 338 a, 339 a is also performed bycooperation of a plurality of pipelayers 100 based on an instructionfrom the hoistman HM.

If either of the centering/joining acts is carried out on a grade, theseacts may proceed as shown in FIG. 16. The pivoted pulley block 135compensates for the grade, thereby maintaining a portion of the cable132 and the load block 140 aligned with a direction of gravity G.

FIG. 17 is an orthogonal view of a pipelayer 400, according to analternative embodiment of the present invention. A second winch 430 isused instead of the PCA 125 to hoist the boom 120. The second winch 430is attached to the adaptor 110 or directly to the main frame 105 andincludes a second drum having a second cable 432 wrapped therearound.The second drum is rotatable relative to a second housing of the secondwinch 430. The second drum may be driven by a hydraulic motor (notshown). Pivoted to the second longitudinal end of the boom 120 is afirst sheave block 435 a. A second sheave block 435 b is pivoted to thesecond winch housing, the adaptor 110, or directly to the main frame105. Each of the sheave blocks 435 a, b includes a plurality of pulleysor sheaves. The cable 132 extends from the second drum and around thesheaves of the sheave blocks 435 a, b in order to achieve a mechanicaladvantage. Unwinding of the cable 432 from the second winch drum lowersthe boom 120 and winding of the cable 432 around the second winch drumraises the boom 120. Loading of the pipelayer 400 is similar to loadingof the pipelayer 100. If the third trailer 200 c is used, the firstsheave block 435 a may simply be removed and loaded on the secondtrailer 200 b with the remaining pipelayer 400 (may depend on whetherthe adaptor 110 is used, see above). Usage and loading of the pipelayer400 is similar to usage and loading of the pipelayer 100.

In another alternative embodiment, the winch 130 may be attached to amodified adaptor instead of the boom 120, for example, proximate to thecab 115. In another alternative embodiment, the second winch 430 may beused instead of the PCA 125 to hoist the boom 120 and both the secondwinch 430 and the winch 130 may be attached to a modified adaptor, forexample, proximate to the cab 115. In another alternative embodiment,the winch 130 may be attached to the main frame 105 instead of the boom120, for example, proximate to the cab 115. In another alternativeembodiment, the boom may be longitudinally extended by adding a secondboom section (not shown) flanged to the boom 120. The flange may includea hinge so that the second boom section may be folded over the boom 120for transportation.

In another alternative embodiment, a modified adaptor (not shown) may beused having a first member pivoted to the first side of the main frameand a second member pivoted to the second side of the main frame, thetwo members also pivoted together. In a one aspect of this alternativeembodiment, the second winch 430 may be used instead of the PCA 125 tohoist the boom 120 and the second winch 430 may be attached to the oneof the adaptor members proximate to the pivot between the members. Inanother aspect of this alternative embodiment, the winch 130 may beattached to the one of the adaptor members proximate to the pivotbetween the members instead of to the boom 120. In another aspect ofthis alternative embodiment, the boom 120 may be pivoted to the firstadaptor member at a location midway along the adaptor member and the PCA125 may be pivoted to the adaptor member at the first side of the mainframe. In another aspect of this alternative embodiment, a second winchmay be used instead of the PCA 125 to hoist the boom 120 and bothwinches 130, 430 may be located on the adaptor members proximate to thepivot between the adaptor members.

FIGS. 18A-D illustrate a removable counterweight system (RCW) 500,according to another embodiment of the present invention. FIG. 18A is aside view of the RCW 500 in a first position where a counterweight 545is removably attached to the main frame 105 (at second side 105 b). FIG.18B is a side view of the RCW 500 in a second position where thecounterweight 545 is removed from the main frame 105 and set on theground. The counterweight 545 is shown separately in FIGS. 18C-D forclarity. FIG. 18C is a front view of the counterweight 545. FIG. 18D isa section view of FIG. 18C taken along line 18D-18D.

The RCW 500 may be installed on the pipelayer 100 in lieu of thecounterweight 145. The RCW 500 may be hydraulically operated between thefirst and second positions. The RCW 500 may be operated from the cab 115and/or from controls (not shown) located on the main frame 105. The RCW500 allows for quick, automated, and independent removal of thecounterweight 545 in instances where the pipelayer 100 (or 400) will beoperated on steep grades. During steep grade operation, thecounterweight 145/545 destabilizes the pipelayer 100 in certainrotational orientations of the main assembly 150 a relative to theundercarriage 150 b and/or loading scenarios. Removal of thecounterweight 545 allows more versatile operation of the pipelayer 100on steep grades. Alternatively or in addition thereto, the weight of thelower frame 160 may be increased by adding weights (not shown) orincreasing the thickness of structural members to compensate for removalof the counterweight 545 and/or increase stability of the pipelayer 100on steep grades. Alternatively or in addition to using the RCW for steepgrade operation, the RCW 500 may be used to load the counterweight 545on the third trailer 200 c (discussed above). Alternatively, thepipelayer 100 may be operated on steep grades without the RCW 500 byrelying on the LMS to safely constrain movement of the pipelayer 100from unstable positions.

The RCW 500 may include a piston and cylinder assembly (PCA) 505, a base510, a head 520, one or more front arms 525 a, one or more rear arms 525b, and the counterweight 545. The base 510 is attached to the main frame105 via lugs. One or more blocks (not shown for clarity) may be attachedto the main frame 105 proximate to the base 510. The PCA 505 is pivotedto the main frame 105 via a lug and pivoted to the head 520. The frontarms 525 a are pivoted to the main frame 105 via lugs and pivoted to thehead 520. The rear arms 525 b are pivoted to the main frame 105 via lugsand pivoted to the head 520. One or more forks 515 are also pivoted tothe head 520. The forks 515 allow the counterweight 545 to be pivoted tothe head 520 by receiving respective eyes 545 e attached to thecounterweight 545. Once holes through the forks are aligned withrespective holes through the eyes 545 e, pins (not shown) are insertedthrough each fork and eye, thereby securing the counterweight 545 to thehead 520. The forks may 515 also be free to rotate about theirlongitudinal axis.

The counterweight 545 includes a body having a recess 545 r formedtherein, one or more blocks 545 b attached thereto and disposed in therecess 545 r, and the eyes 545 e attached thereto and disposed in therecess. The eyes 545 e may be attached to the body via the blocks 545 b.When the counterweight 545 is in the first position, the PCA 505, thebase 510, the arms 525 a, b, and the forks 515 may be disposed in therecess 545 r. The head 520 may extend upward out of the recess 545 r orbe disposed in the recess 545 r as well.

Starting from the first position where the PCA 505 is fully extended,retraction of the PCA 505 articulates the head 520 (and thecounterweight 545) horizontally away from the main frame 105 andvertically downward until the counterweight 545 is seated on the ground.The front 525 a and rear 525 b arms support the head 520 as itarticulates between the first and second positions. Once thecounterweight 545 is seated on the ground, the pins may be removed andthe head 520 may be returned to the first position to stow it forpipelayer operation without the counterweight 545. To re-attach thecounterweight 545, the process is reversed. The head 520 is articulatedto the second position, the pins inserted, and the PCA extended.Extension of the PCA articulates the head 520 (and the counterweight545) vertically upward and horizontally toward the main frame 105 untilbottoms of the blocks 545 b are seated on the base 510 and faces of theblocks 545 b abut the base blocks. One or more safety latch mechanisms(not shown) may be actuated (manually or automatically) once thecounterweight 545 is seated on the base 510. Further, a proximity sensormay be provided to verify that the counterweight has properly seated.

FIGS. 19-21 illustrate an excavator 600 and acts of a method forpartially disassembling the excavator 600 and loading the excavator ontwo or more tractor-trailers 200 a-c (only trailer shown and gooseneckremoved for simplicity) for transporting the excavator 600 between worksites over public roads, according to another embodiment of the presentinvention. Acts similar to those described above with reference to FIGS.7-12 will not be repeated. The excavator 600 may be the pipelayer 100after the adapter 110 and the boom 120 have been removed and anexcavator boom assembly 620 attached to the main frame 105. Theexcavator boom assembly 620 includes a boom 620 a pivoted to the mainframe 105 at a first end thereof and an arm or stick 620 b pivoted tothe second end of the boom 620 a at a first end thereof. One or morefirst PCAs 625 a are pivoted to the main frame and pivoted to the boom620 a for articulating the first boom to the main frame 105. A secondPCA 625 b is pivoted to the boom 620 a and pivoted to the stick 620 bfor articulating the stick 620 b relative to the boom 620 a. A bucket640 is pivoted to the second end of the stick 620 b. A third PCA 625 cis pivoted to the stick 620 b and to the bucket 640 via a linkage forarticulating the bucket 640 relative to the stick 620 b.

FIG. 19 illustrates the outriggers 165 in the extended position and afirst act of loading one of the track assemblies 175 on the firsttrailer 200 a. FIG. 20 illustrates a second act of loading one of thetrack assemblies on the first trailer 200 a. First and second eyes 690a, b are attached to the boom 620 a and the stick 620 b, respectively.The second eye 690 b is optional as an eye located on the back of thebucket 640 may be used instead. Once the track assembly 175 is ready tobe removed, the boom assembly 620 is articulated to the position shownand the clamp 250 is secured to the first eye 690 a with a cable. Theboom assembly 620 is raised to lift the track assembly 175 from thebrackets 195. The track assembly 175 will then swing away from theremaining excavator 600. The boom assembly 620 may then be lowered andthe track assembly 175 set on the ground. In this position, the boomassembly 620 may then be articulated so the clamp 250 (and cable) may besecured to the second eye 690 b. Once the clamp 250 is secured to thesecond eye 690 b, the boom assembly 620 may be articulated to load thetrack assembly 175 onto the first tractor-trailer 200 a. The acts maythen be repeated to load the other track assembly 175 onto the firsttractor-trailer 200 a (with the addition of rotating the main assembly150 a about the undercarriage 150 b).

Alternatively, a winch (not shown) may be attached to the boom assembly620 instead of the eyes 690 a, b for hoisting the track assemblies. Thewinch may be attached to the stick 620 b near the bucket 640. In thisalternative, the clamp 250 would be connected to the winch cable and thewinch would then be operated to lift and swing the track assembly overto the winch. The boom assembly would then be articulated to lower thetrack assembly onto the tractor trailer 200 a.

FIG. 21 illustrates the remaining excavator 600 loaded on the secondtrailer 200 b. Once the track assemblies 175 have been loaded on thefirst tractor trailer 200 a, the remaining excavator 600 may be loadedonto the second tractor trailer 200 b. The boom assembly 620 may bearticulated so that the arm 620 b is folded underneath the boom 620 a.Since the stick 620 b can be folded underneath the boom 620 a, thestinger trailer 205 is not required. As discussed above with referenceto FIG. 12, if it is necessary to reduce the weight of the secondtrailer 200 b, the counterweight 145 and/or the boom assembly 620 may beloaded on a third tractor-trailer 200 c.

FIGS. 22 and 23 illustrate acts of a method for partially disassemblingthe excavator 600 (or pipelayer 100, 400) and loading the excavator 600on two or more tractor-trailers 200 a-c (only trailer shown) fortransporting the excavator 600 between work sites over public roads,according to another embodiment of the present invention. FIG. 22illustrates the excavator 600 driven over the trailer 200 b after agooseneck 210 of the trailer has been removed. FIG. 23 illustrates theexcavator 600 lifted off the track shoes 120 by a gooseneck jack 215.

In this embodiment, the excavator 600 or the pipelayer 100 may be loadedfor transportation without requiring the outriggers 165. Instead ofraising the excavator 600 or the pipelayer 100 off of the track shoesusing the outriggers 165, the gooseneck jack 215 is used. As shown, theboom assembly 620 is in the folded position; however, the boom assemblymay also be in the position illustrated in FIGS. 19 and 20. The trailer200 b is removed from the tractor and a front end of the trailer 200 bset on the ground. The gooseneck 210 of the trailer 200 b is removedfrom a front end of the trailer 200 b. The excavator 600 or thepipelayer 100 is driven over the trailer 200 b via the front end andparked. Wood blocks may be placed between the lower frame 160 and thetrailer 200 b. The gooseneck 210 is reattached to the front end of thetrailer 200 b. The jack 215 included with the gooseneck 210 is used toraise the front end off the ground, thereby also raising the excavator600 or the pipelayer 100 off of the track shoes 120. The jack 215 may beoperated using one or more hydraulic lines (not shown) connected to ahydraulic pump of the truck.

The weight may then be transferred from the gooseneck jack 215 to one ormore jack stands (not shown). The lower frame 160 may be chained down tothe trailer 200 b. Removal and loading of the track assemblies 175 ontothe trailer 200 a may then proceed as shown in FIGS. 19-20 or FIGS. 7-8and as discussed above. The trailer 200 b may be attached to the tractorand the remaining excavator 600 or the pipelayer 100 transported to thenext worksite using the trailer 200 b (after folding the boom assembly620 or after lowering the boom 120 and hitching the stinger 205 (ifneeded) as in FIG. 11). Alternatively, as discussed above, the boom 120,boom assembly 620, and/or the counterweight 145 may be removed from theremaining excavator 600 or the pipelayer 100 and loaded on the trailer200 c. Alternatively, a lowboy beam trailer (not shown) may be usedinstead of a lowboy flatbed trailer.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for transporting a pipelayer or excavator from a first worksite to a second worksite via a public road, comprising acts of: raisingthe pipelayer or excavator off of track shoes of the pipelayer orexcavator; removing a first track assembly from the pipelayer orexcavator using a boom of the pipelayer or a boom assembly of theexcavator; loading the first track assembly onto a first trailer of afirst tractor-trailer using the boom of the remaining pipelayer or theboom assembly of the remaining excavator; removing the second trackassembly from the pipelayer using the boom of the remaining pipelayer orthe boom assembly of the remaining excavator; and loading the secondtrack assembly onto the first trailer using the boom of the remainingpipelayer or the boom assembly of the remaining excavator.
 2. The methodof claim 1, further comprising: backing a second trailer of a secondtractor-trailer underneath the remaining pipelayer or excavator; andlowering the remaining pipelayer or excavator onto the second trailer.3. The method of claim 2, further comprising transporting the pipelayeror the excavator to the second worksite using only the twotractor-trailers.
 4. The method of claim 2, further comprising: removingthe boom and/or a counterweight of the pipelayer or excavator from theremaining pipelayer or excavator; and loading the boom and/or thecounterweight onto a third trailer of a third tractor-trailer.
 5. Themethod of claim 4, wherein the counterweight is removed and loaded andremoving and loading the counterweight comprises operating a piston andcylinder assembly of the pipelayer or excavator.
 6. The method of claim2, further comprising hitching a stinger trailer to the second trailer.7. The method of claim 1, wherein raising the pipelayer or excavatorcomprises operating outriggers of the pipelayer or excavator.
 8. Themethod of claim 1, wherein the pipelayer or excavator is the pipelayer.9. The method of claim 10, wherein the pipelayer comprises: anundercarriage, comprising: a lower frame; two track assemblies, eachtrack assembly, comprising: a track frame removably attached to thelower frame; and a track shoe supported by the track frame so that thetrack shoe may move around the track frame; a main assembly supported bythe undercarriage so that the main assembly may rotate relative to theundercarriage, the main assembly comprising: a main frame; and the boompivoted to the main frame.
 10. The method of claim 1, wherein thepipelayer or excavator is the excavator.
 11. The method of claim 10,wherein removing each track assembly uses a boom of the boom assemblyand loading each track assembly uses a stick of the boom assembly. 12.The method of claim 10, wherein removing each track assembly uses awinch attached to the boom assembly.
 13. The method of claim 10, furthercomprising folding a stick of the boom assembly underneath a boom of theboom assembly.
 14. The method of claim 1, wherein raising the pipelayeror excavator comprises operating a jack of a second trailer.
 15. Themethod of claim 14, further comprising: removing a gooseneck from afront end of the second trailer; driving the pipelayer or excavator overthe second trailer via the front end; and reattaching the gooseneck tothe front end of the second trailer.
 16. A pipelayer, comprising: anundercarriage, comprising: a lower frame; two track assemblies, eachtrack assembly, comprising: a track frame removably attached to thelower frame; and a track shoe supported by the track frame so that thetrack shoe may move around the track frame; a main assembly supported bythe undercarriage so that the main assembly may rotate relative to theundercarriage, the main assembly comprising: a main frame; and a boompivoted to the main frame.
 17. The pipelayer of claim 16, furthercomprising an adaptor removably attached to the main frame, wherein theboom is pivoted to the adaptor.
 18. The pipelayer of claim 16, furthercomprising a winch attached to the boom.
 19. The pipelayer of claim 16,wherein the boom is an A-frame.
 20. The pipelayer of claim 19, whereinthe boom is asymmetric.
 21. The pipelayer of claim 16, furthercomprising: a winch; a cable operatively connected to the winch; and apulley block operatively connected to the cable and pivoted to the boom.22. The pipelayer of claim 21, wherein the pivot between the pulleyblock and the boom is a hinge.
 23. The pipelayer of claim 21, furthercomprising a load block operatively connected to the cable.
 24. Thepipelayer of claim 16, further comprising a piston and cylinder assemblypivoted to the boom and pivoted to the main frame.
 25. A method of usingthe pipelayer of claim 16, comprising: lifting a pipe using thepipelayer; rotating the pipe about a radius using the pipelayer; andlowering the pipe into a trench using the pipelayer.
 26. A method ofusing the pipelayer of claim 17, comprising: removing the adaptor andthe boom; and attaching an excavator boom or a crane boom to the mainframe.
 27. The pipelayer of claim 16, further comprising a cab attachedto the main frame, wherein an operator's field of vision to a front, aleft, and a right side is unobstructed when an operator is seated in thecab.
 28. The pipelayer of claim 16, further comprising an outriggerpivoted to the lower frame, the outrigger operable to extend intocontact with the ground to support the pipelayer.
 29. The pipelayer ofclaim 28, wherein the outrigger comprises: a first arm pivoted to thelower frame and operable between a first position along the lower frameand a second position extending from the lower frame; and a second armoperable between a first position retracted in the first arm and asecond position extended from the first arm.
 30. The pipelayer of claim29, wherein the outrigger further comprises: a third arm operablebetween a first position retracted in the second arm and a secondposition extended from the second arm; and a pad pivoted to the thirdarm.
 31. The pipelayer of claim 16, further comprising a track motorattached to the track frame, wherein the track shoe is operativelyconnected to the track motor.
 32. The pipelayer of claim 16, furthercomprising an engine attached to the main frame.
 33. The pipelayer ofclaim 32, wherein the engine is a diesel-electric hybrid.
 34. Thepipelayer of claim 32, wherein the engine is a hydrogen fuel-cell. 35.The pipelayer of claim 16, wherein a length of the lower frame issubstantially equal to or less than a width of a standard trailer of atractor-trailer.
 36. The pipelayer of claim 16, wherein a width of thelower frame is greater than a width of a standard trailer of atractor-trailer.
 37. The pipelayer of claim 16, wherein a width of theundercarriage is not variable.
 38. The pipelayer of claim 16, wherein:the removable attachment between the track frame and the lower framecomprises a lug and a bracket assembly, the lug comprises a hook and ahole, the lug is attached to one of the track frame and the lower frame,the bracket assembly is attached to the other of the track frame and thelower frame, and the bracket assembly comprises a first fastener whichreceives the hook and a second removable fastener disposed through thehole.
 39. The pipelayer of claim 16, further comprising: a winchattached to the main frame; and a cable operatively connected to thewinch and to the boom at an end of the boom distal from the pivotbetween the boom and the main frame so that operation of the winch willraise or lower the boom.
 40. The pipelayer of claim 16, wherein arectangular inner footprint is defined by inner sides of the track shoesand the pivot between the boom and the main frame is located within theinner footprint.
 41. The pipelayer of claim 40, wherein the pivotbetween the boom and the main frame is located within the innerfootprint at any rotational orientation of the main frame relative tothe undercarriage.
 42. The pipelayer of claim 16, wherein: the boom ispivoted to a first side of the main frame, and the main assembly furthercomprises a counterweight removably attached to a second side of themain frame, the second side opposite the first side.
 43. The pipelayerof claim 42, further comprising: a piston and cylinder assembly (PCA)pivoted to the main frame and pivoted to the counterweight, wherein thePCA is operable between a first position where the counterweight isremovably attached to the second side of the main frame and a secondposition where the counterweight is seated on the ground.
 44. Thepipelayer of claim 43, further comprising: a head pivoted to thecounterweight; a first pair of arms pivoted to the main frame and thehead; a second pair of arms pivoted to the main frame and the head,wherein the PCA is pivoted to the counterweight via the head.
 45. Thepipelayer of claim 42, wherein the counterweight has a recess formedtherein and the PCA is disposed in the recess when the PCA is in thefirst position.
 46. The pipelayer of claim 42, further comprising aproximity sensor operable to verify that the counterweight is in thefirst position.
 47. A method of using a pipelayer, comprising acts of:providing a pipelayer; removing a counterweight of the pipelayer; andoperating the pipelayer on a steep grade without the counterweight. 48.The method of claim 47, wherein removing the counterweight comprisesoperating a piston and cylinder assembly of the pipelayer.
 49. Themethod of claim 47, wherein a weight of an undercarriage of thepipelayer has been increased to compensate for removal of thecounterweight.